A propane gas leak caused by an unsecured gas line to a home led to the explosion, according to Fire Marshal Jim Tortora.

Pioneer owner William Papale said his employees were at the house to change over the homeowner's service from another company to Pioneer, which is a routine job. He said there was already an existing gas system in the home and all they needed to do was put in a new propane tank.

He said safety is his company's "No. 1 concern" and that this is the first time in the 70 years the company has been in business that "something like this has happened."

Before the explosion occurred, two other occupants of the house, Debra Duguid, 53, and her daughter, were told to go outside when workers smelled gas. Duguid and her daughter were not injured in the 2 p.m. blast, but were in shock because of what happened.

Neighbor Bart Bakota, 20, heard the explosion and said he saw flames shooting from the house, which is across the street from his, and then saw three men coming out of the building.

"They were all badly burned," said Bakota. "They had burns all over their face, head, legs, hands and back." Parts of their clothes were burned off and their hair singed, he said.

Police and fire officials said the main beam of the house was shattered and the basement walls were blown out.